Low-Field Magnetic Sensing with GMR Sensors

Industry continues to reap the benefits of
solid state magnetic field sensing. Every day new
applications are found for solid state magnetic field
sensors due to their small size, low power. And
relatively low cost. The new frontier for these solid
state sensors is very low magnetic fields; the kinds
encountered when looking for geophysical anomalies,
either natural or man-made, various physiological
functions, metal defects, magnetic ink and minute
magnetic particles associated with immunoassay. In
the past, equipment to perform many of these
functions has required a substantial amount of power
and has been quite large. In addition, because of their
size, the equipment has become costly. Leveraging
on substantial government efforts, GMR technology is
being applied to these applications today and the
newer GMR technologies such as Spin Dependent
Tunneling (SDT) will make even more of these
applications possible. As with all of solid state
technology, many of the now difficult measurements
will become more commonplace and provide the
ingredients for more precise measurement, diagnosis,
and control. Several applications will be presented on
the use of individual sensors and arrays being used to
address some of these new areas.